In general, construction machinery including an excavator is capable of travelling and rotating, and performing work, such as excavation, by using a front working device, such as a boom, an arm, and a bucket, while travelling and rotating, or being in a stop state.
The construction machinery is capable of travelling in three modes including a low speed mode, a high speed mode, and an automatic transmission mode, and when the construction machinery travels in the automatic transmission mode, a speed is automatically changed to a low speed or a high speed according to loads applied to the front working device.
For the automatic transmission travel mode, the construction machinery detects hydraulic pressure applied from a main hydraulic pump to an actuator, such as a cylinder and a hydraulic motor, through a pressure sensor, and changes a travel speed into a low speed or a high speed according to the detected pressure.
That is, the construction machinery measures a size of loads based on the hydraulic pressure detected by the pressure sensor, and when the size of the loads is large, the construction machinery travels at a low speed, and when the size of the loads is small, the construction machinery travels at a high speed.
However, the aforementioned construction machinery in the related art determines a size of loads while relaying on only the pressure sensor during the automatic transmission travel. Accordingly, when the pressure sensor has a breakdown, the construction machinery cannot use the function even though the automatic transmission travel mode is selected, and when the pressure sensor has a malfunction, a safety accident may be incurred due to incorrect automatic travelling.
The discussion above is merely provided for general background information and is not intended to be used as an aid in determining the scope of the claimed subject matter.